148 children and adolescents with Lyme borreliosis and tick bite or suspection on tick bite were examined. The examined patients were aged from 14 months to 24 years and divided into four age groups. Skin lesions were discovered in 25 percent of patients with tick bite. Erythema migrans occurred in 91 percent, Lymphocytoma in 3 percent and sclerodermatous lesions (Lichen sclerosus et atrophicus and Morphea) in 6 percent of patients with Lyme disease. Serologic tests on the presence of antibodies to Borreliae burgdorferi were performed in 96 percent of cases with tick bite. Antibody titer 1:80 or higher in 8 percent of patients with tick bite, was discovered. We found positive serologic test results in 5 (29 percent) of 29 persons with Erythema migrans, in 4 (4 percent) of 110 patients with tick bite (without skin lesions), as well as, in 1 patient with Lymphocytoma. Antibiotic therapy was applied in all cases with Erythema migrans, in person with Lymphocytoma, as well as, in patients with asymptomatic infections (patients without skin lesion recalling a tick bite and with antibodies against Borrelia burgdorferi). A general sensitivity, to infection with Borrelia burgdorferi, is stressed, a fact based on appearance by Lyme borreliosis in all age groups even in the newborn children.